Bioscience Blog

A Bountiful Harvest of Crop Science Publications

Metabolix produces a range of PHA bioplastic products for its commercial customers using a proprietary industrial fermentation and biopolymer recovery process. The fermentation process is driven by microbes specifically engineered by Metabolix to produce PHAs with certain technical characteristics. The scientific advances in metabolic pathway engineering developed by Metabolix researchers over the last 15 years to engineer production microbes provided the foundation to apply this advanced metabolic engineering expertise to plants.

In our crop science program, Metabolix researchers have developed high throughput transformation systems and advanced metabolic engineering informed by bioinformatics around making PHB, the simplest member of the PHA bioplastic family, as a means to produce biobased, biodegradable plastics and renewable chemicals in non-food crop plants. Producing PHB bioplastic in significant quantities in plant cells—and there are many different types— is hard. Really hard.

So in tandem with figuring out how to produce PHB bioplastic in plants, Metabolix researchers have also had to figure out how to make the plants more robust and to address the practical considerations of introducing “plant factories” into the field. As this research has evolved, Metabolix has made some important discoveries that hold the potential to engineer traits into a variety of plant species. This advance can be summed up by the term “enhanced carbon capture and targeted deposition” in other words enabling the plant to fix more carbon dioxide from the atmosphere and directing that additional fixed carbon through metabolic engineering to the product of interest, in the first case PHB bioplastic. At Metabolix, we believe this approach can be applied to major row crops and other crop products of interest including starches and oils. One of the key conclusions we have reached from over a decade of research on this challenging problem is that step changes in crop performance can really only be achieved by using gene combinations. In fact, at Metabolix we believe that advanced multi-gene metabolic pathway engineering will be essential to achieve steps changes in crop and crop product yield.

Switchgrass growing in Metabolix’s greenhouse.

Metabolix researchers have co-authored 8 papers in 2014 related to crop science and the recovery of chemicals from crops. Visit the Publications page on our website for a listing and link to the papers.

Here is a brief summary of the published findings:

Achieved an important advance towards the establishment of a reliable biocontainment system for switchgrass, which has the potential to facilitate further development of this crop as a biorefinery feedstock. BMC Biotechnology.

Described a method to increase production of high molecular weight PHB in the oilseed Camelina. Achieved levels of up to 15% PHB in first generation seeds, the highest reported to date in seeds. The team also achieved up to 13.7% PHB in seeds of later plant generations. Plant Biotechnology Journal.

Identified factors that limit the production of PHB in some cell types in sugar cane and switchgrass. BMC Biotechnology.

Demonstrated a process to produce bio-n-butanol, a chemical with value as a fuel and as a commodity chemical, from crotonic acid. Crotonic acid can be produced from PHB containing switchgrass biomass. Organic Process Research and Development.

Demonstrated a process to produce acrylates, important industrial chemicals, from crotonates. This work is part of Metabolix’s continuing efforts to develop a process to produce crotonic acid as a bio-based platform chemical that can be extracted and purified from PHB producing plants. Organic Process Research and Development.

Engineered a new pathway to produce high molecular weight PHB in the mesophyll cells of sugar cane, allowing for PHB levels of up to 11.8% in leaf tissue, the highest level ever recorded in sugarcane. Plant Biotechnology Journal.

Metabolix scientists collaborated with the following research organizations during the course of some of the plant science research: researchers at the USDA Agricultural Research Service in Albany, California for the work on switchgrass gene containment; researchers at the Eastern Regional Research Center of the USDA Agricultural Research Service in Wyndmoor, Pennsylvania for the recovery of crotonic acid from PHB switchgrass mixtures and the conversion of crotonic acid to bio-n-butanol; scientists at The Donald Danforth Plant Science Center in St. Louis, Missouri for work to produce PHB in Camelina; scientists at the University of Queensland in Brisbane, Australia for the work in sugar cane; and scientists at The University of North Texas for the review paper on production of novel biopolymers in plants.

Special thanks to Dr. Kristi Snell and Dr. Oliver Peoples for reviewing this blog article.